Method and apparatus for transceiving messages from v2x terminal in wireless communication system

ABSTRACT

One embodiment of the present invention relates to a method for a terminal transmitting a message in a wireless communication system, comprising the steps of: generating a message; and transmitting, from a resource sectioned on a time axis, control information for the message and the message when the size of the message is larger than a predetermine value, and transmitting, from a resource sectioned on a frequency axis, the control information for the message and the message when the size of the message is smaller than the predetermined value.

TECHNICAL FIELD

Following description relates to a wireless communication system, andmore particularly, to a method for a V2X (vehicle to everything) UE totransmit control information and a message and an apparatus therefor.

BACKGROUND ART

Wireless communication systems have been widely deployed to providevarious types of communication services such as voice or data. Ingeneral, a wireless communication system is a multiple access systemthat supports communication of multiple users by sharing availablesystem resources (a bandwidth, transmission power, etc.) among them. Forexample, multiple access systems include a Code Division Multiple Access(CDMA) system, a Frequency Division Multiple Access (FDMA) system, aTime Division Multiple Access (TDMA) system, an Orthogonal FrequencyDivision Multiple Access (OFDMA) system, a Single Carrier FrequencyDivision Multiple Access (SC-FDMA) system, and a Multi-Carrier FrequencyDivision Multiple Access (MC-FDMA) system.

D2D communication is a communication scheme in which a direct link isestablished between User Equipments (UEs) and the UEs exchange voice anddata directly without an evolved Node B (eNB). D2D communication maycover UE-to-UE communication and peer-to-peer communication. Inaddition, D2D communication may be applied to Machine-to-Machine (M2M)communication and Machine Type Communication (MTC).

D2D communication is under consideration as a solution to the overheadof an eNB caused by rapidly increasing data traffic. For example, sincedevices exchange data directly with each other without an eNB by D2Dcommunication, compared to legacy wireless communication, networkoverhead may be reduced. Further, it is expected that the introductionof D2D communication will reduce procedures of an eNB, reduce the powerconsumption of devices participating in D2D communication, increase datatransmission rates, increase the accommodation capability of a network,distribute load, and extend cell coverage.

Currently, discussion on V2X communication associated with D2Dcommunication is in progress. The V2X communication corresponds to aconcept including V2V communication performed between vehicle UEs, V2Pcommunication performed between a vehicle and a UE of a different type,and V2I communication performed between a vehicle and an RSU (roadsideunit).

DISCLOSURE OF THE INVENTION Technical Task

A technical task of the present invention is to provide a method ofconfiguring various resource structures capable of transmitting controlinformation and a message transmitted by a V2X UE.

Technical tasks obtainable from the present invention are non-limited bythe above-mentioned technical task. And, other unmentioned technicaltasks can be clearly understood from the following description by thosehaving ordinary skill in the technical field to which the presentinvention pertains.

Technical Solution

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, accordingto one embodiment, a method of transmitting a message, which istransmitted by a user equipment (UE) in a wireless communication system,includes the steps of generating a message, and if a size of the messageis greater than a predetermined value, transmitting control informationfor the message and the message in a resource distinguished on a timeaxis, and if the size of the message is less than the predeterminedvalue, transmitting the control information for the message and themessage in a resource distinguished on a frequency axis.

To further achieve these and other advantages and in accordance with thepurpose of the present invention, according to a different embodiment, auser equipment (UE) in a wireless communication system includes atransmitter and a receiver, and a processor, the processor configured togenerate a message, the processor, if a size of the message is greaterthan a predetermined value, configured to transmit control informationfor the message and the message in a resource distinguished on a timeaxis, the processor, if the size of the message is less than thepredetermined value, configured to transmit the control information forthe message and the message in a resource distinguished on a frequencyaxis.

If the control information and the message are transmitted in theresource distinguished on the frequency axis, the control informationfor the message can be transmitted from at least one or more regionsamong a plurality of preconfigured candidate regions.

The preconfigured candidate regions may consist of slots on the timeaxis and the preconfigured number of resource blocks (RBs) on thefrequency axis.

A position of a candidate region in which the control information isincluded in a second slot can be restricted by a position of a candidateregion in which the control information is included in a first slot.

A candidate region in which the control information is included in asecond slot and a candidate region in which the control information isincluded in a first slot can be positioned at a different frequencyband.

A center RB of the entire frequency band may not be included in aplurality of the preconfigured candidate regions.

The message is transmitted in a region selected from the groupconsisting of a region within +/−K1 RBs, a region within +K2 RBs, and aregion within −K3 RBs from an RB in which the control information istransmitted and the K1, the K2, and the K3 may correspond to naturalnumbers.

The message may correspond to a V2X (vehicle to everything) message.

The control information can include at least one selected from the groupconsisting of an ID, a UE type indicating a type of the UE among a P-UE,a V-UE, and an RSU, a hopping flag, and RA (resource allocation).

If the control information does not include the ID, a DMRS basesequence, CS (cyclic shift), OCC, and a scrambling sequence can begenerated using one selected from the group consisting of the UE type,the hopping flag, and the RA.

A message larger than the predetermined value may correspond to aperiodic message and a message smaller than the predetermined value maycorrespond to an event triggered message.

Advantageous Effects

According to the present invention, it is able to transmit controlinformation and a message according to a message size using a differentmultiplexing scheme without a loss on a cubic metric.

Effects obtainable from the present invention are non-limited by theabove mentioned effect. And, other unmentioned effects can be clearlyunderstood from the following description by those having ordinary skillin the technical field to which the present invention pertains.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a diagram for a structure of a radio frame;

FIG. 2 is a diagram for a resource grid in a downlink slot;

FIG. 3 is a diagram for a structure of a downlink subframe;

FIG. 4 is a diagram for a structure of an uplink subframe;

FIG. 5 is a diagram for a configuration of a wireless communicationsystem having multiple antennas;

FIG. 6 is a diagram for a subframe in which a D2D synchronization signalis transmitted;

FIG. 7 is a diagram for explaining relay of a D2D signal;

FIG. 8 is a diagram for an example of a D2D resource pool for performingD2D communication;

FIG. 9 is a diagram for explaining an SA period;

FIGS. 10 and 11 illustrate a simulation result for an impact of cubicmetric according to an embodiment of the present invention;

FIGS. 12 to 23 are diagrams illustrating a resource structure/resourceallocation method according to an embodiment of the present invention;

FIG. 24 is a diagram for configurations of a transmitter and a receiver.

BEST MODE Mode for Invention

The embodiments of the present invention described hereinbelow arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions or features ofany one embodiment may be included in another embodiment and may bereplaced with corresponding constructions or features of anotherembodiment.

In the embodiments of the present invention, a description is made,centering on a data transmission and reception relationship between aBase Station (BS) and a User Equipment (UE). The BS is a terminal nodeof a network, which communicates directly with a UE. In some cases, aspecific operation described as performed by the BS may be performed byan upper node of the BS.

Namely, it is apparent that, in a network comprised of a plurality ofnetwork nodes including a BS, various operations performed forcommunication with a UE may be performed by the BS or network nodesother than the BS. The term ‘BS’ may be replaced with the term ‘fixedstation’, ‘Node B’, ‘evolved Node B (eNode B or eNB)’, ‘Access Point(AP)’, etc. The term ‘relay’ may be replaced with the term ‘Relay Node(RN)’ or ‘Relay Station (RS)’. The term ‘terminal’ may be replaced withthe term ‘UE’, ‘Mobile Station (MS)’, ‘Mobile Subscriber Station (MSS)’,‘Subscriber Station (SS)’, etc.

The term “cell”, as used herein, may be applied to transmission andreception points such as a base station (eNB), sector, remote radio head(RRH) and relay, and may also be extensively used by a specifictransmission/reception point to distinguish between component carriers.

Specific terms used for the embodiments of the present invention areprovided to help the understanding of the present invention. Thesespecific terms may be replaced with other terms within the scope andspirit of the present invention.

In some cases, to prevent the concept of the present invention frombeing ambiguous, structures and apparatuses of the known art will beomitted, or will be shown in the form of a block diagram based on mainfunctions of each structure and apparatus. Also, wherever possible, thesame reference numbers will be used throughout the drawings and thespecification to refer to the same or like parts.

The embodiments of the present invention can be supported by standarddocuments disclosed for at least one of wireless access systems,Institute of Electrical and Electronics Engineers (IEEE) 802, 3rdGeneration Partnership Project (3GPP), 3GPP Long Term Evolution (3GPPLTE), LTE-Advanced (LTE-A), and 3GPP2. Steps or parts that are notdescribed to clarify the technical features of the present invention canbe supported by those documents. Further, all terms as set forth hereincan be explained by the standard documents.

Techniques described herein can be used in various wireless accesssystems such as Code Division Multiple Access (CDMA), Frequency DivisionMultiple Access (FDMA), Time Division Multiple Access (TDMA), OrthogonalFrequency Division Multiple Access (OFDMA), Single Carrier-FrequencyDivision Multiple Access (SC-FDMA), etc. CDMA may be implemented as aradio technology such as Universal Terrestrial Radio Access (UTRA) orCDMA2000. TDMA may be implemented as a radio technology such as GlobalSystem for Mobile communications (GSM)/General Packet Radio Service(GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may beimplemented as a radio technology such as IEEE 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE 802.20, Evolved-UTRA (E-UTRA) etc. UTRA is a partof Universal Mobile Telecommunications System (UMTS). 3GPP LTE is a partof Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA fordownlink and SC-FDMA for uplink. LTE-A is an evolution of 3GPP LTE.WiMAX can be described by the IEEE 802.16e standard (WirelessMetropolitan Area Network (WirelessMAN)-OFDMA Reference System) and theIEEE 802.16m standard (WirelessMAN-OFDMA Advanced System). For clarity,this application focuses on the 3GPP LTE and LTE-A systems. However, thetechnical features of the present invention are not limited thereto.

LTE/LTE-A Resource Structure/Channel

With reference to FIG. 1, the structure of a radio frame will bedescribed below.

In a cellular Orthogonal Frequency Division Multiplexing (OFDM) wirelessPacket communication system, uplink and/or downlink data Packets aretransmitted in subframes. One subframe is defined as a predeterminedtime period including a plurality of OFDM symbols. The 3GPP LTE standardsupports a type-1 radio frame structure applicable to Frequency DivisionDuplex (FDD) and a type-2 radio frame structure applicable to TimeDivision Duplex (TDD).

FIG. 1(a) illustrates the type-1 radio frame structure. A downlink radioframe is divided into 10 subframes. Each subframe is further dividedinto two slots in the time domain. A unit time during which one subframeis transmitted is defined as a Transmission Time Interval (TTI). Forexample, one subframe may be 1 ms in duration and one slot may be 0.5 msin duration. A slot includes a plurality of OFDM symbols in the timedomain and a plurality of Resource Blocks (RBs) in the frequency domain.Because the 3GPP LTE system adopts OFDMA for downlink, an OFDM symbolrepresents one symbol period. An OFDM symbol may be referred to as anSC-FDMA symbol or symbol period. An RB is a resource allocation unitincluding a plurality of contiguous subcarriers in a slot.

The number of OFDM symbols in one slot may vary depending on a CyclicPrefix (CP) configuration. There are two types of CPs: extended CP andnormal CP. In the case of the normal CP, one slot includes 7 OFDMsymbols. In the case of the extended CP, the length of one OFDM symbolis increased and thus the number of OFDM symbols in a slot is smallerthan in the case of the normal CP. Thus when the extended CP is used,for example, 6 OFDM symbols may be included in one slot. If channelstate gets poor, for example, during fast movement of a UE, the extendedCP may be used to further decrease Inter-Symbol Interference (ISI).

In the case of the normal CP, one subframe includes 14 OFDM symbolsbecause one slot includes 7 OFDM symbols. The first two or three OFDMsymbols of each subframe may be allocated to a Physical Downlink ControlCHannel (PDCCH) and the other OFDM symbols may be allocated to aPhysical Downlink Shared Channel (PDSCH).

FIG. 1(b) illustrates the type-2 radio frame structure. A type-2 radioframe includes two half frames, each having 5 subframes, a DownlinkPilot Time Slot (DwPTS), a Guard Period (GP), and an Uplink Pilot TimeSlot (UpPTS). Each subframe is divided into two slots. The DwPTS is usedfor initial cell search, synchronization, or channel estimation at a UE.The UpPTS is used for channel estimation and acquisition of uplinktransmission synchronization to a UE at an eNB. The GP is a periodbetween an uplink and a downlink, which eliminates uplink interferencecaused by multipath delay of a downlink signal. One subframe includestwo slots irrespective of the type of a radio frame.

The above-described radio frame structures are purely exemplary and thusit is to be noted that the number of subframes in a radio frame, thenumber of slots in a subframe, or the number of symbols in a slot mayvary.

FIG. 2 illustrates the structure of a downlink resource grid for theduration of one downlink slot. A downlink slot includes 7 OFDM symbolsin the time domain and an RB includes 12 subcarriers in the frequencydomain, which does not limit the scope and spirit of the presentinvention. For example, a downlink slot may include 7 OFDM symbols inthe case of the normal CP, whereas a downlink slot may include 6 OFDMsymbols in the case of the extended CP. Each element of the resourcegrid is referred to as a Resource Element (RE). An RB includes 12×7 REs.The number of RBs in a downlink slot, NDL depends on a downlinktransmission bandwidth. An uplink slot may have the same structure as adownlink slot.

FIG. 3 illustrates the structure of a downlink subframe. Up to threeOFDM symbols at the start of the first slot in a downlink subframe areused for a control region to which control channels are allocated andthe other OFDM symbols of the downlink subframe are used for a dataregion to which a PDSCH is allocated. Downlink control channels used inthe 3GPP LTE system include a Physical Control Format Indicator CHannel(PCFICH), a Physical Downlink Control CHannel (PDCCH), and a PhysicalHybrid automatic repeat request (HARQ) Indicator CHannel (PHICH). ThePCFICH is located in the first OFDM symbol of a subframe, carryinginformation about the number of OFDM symbols used for transmission ofcontrol channels in the subframe. The PHICH delivers an HARQACKnowledgment/Negative ACKnowledgment (ACK/NACK) signal in response toan uplink transmission. Control information carried on the PDCCH iscalled Downlink Control Information (DCI). The DCI transports uplink ordownlink scheduling information, or uplink transmission power controlcommands for UE groups. The PDCCH delivers information about resourceallocation and a transport format for a Downlink Shared CHannel(DL-SCH), resource allocation information about an Uplink Shared CHannel(UL-SCH), paging information of a Paging CHannel (PCH), systeminformation on the DL-SCH, information about resource allocation for ahigher-layer control message such as a Random Access Responsetransmitted on the PDSCH, a set of transmission power control commandsfor individual UEs of a UE group, transmission power controlinformation, Voice Over Internet Protocol (VoIP) activation information,etc. A plurality of PDCCHs may be transmitted in the control region. AUE may monitor a plurality of PDCCHs. A PDCCH is formed by aggregatingone or more consecutive Control Channel Elements (CCEs). A CCE is alogical allocation unit used to provide a PDCCH at a coding rate basedon the state of a radio channel. A CCE includes a plurality of REgroups. The format of a PDCCH and the number of available bits for thePDCCH are determined according to the correlation between the number ofCCEs and a coding rate provided by the CCEs. An eNB determines the PDCCHformat according to DCI transmitted to a UE and adds a Cyclic RedundancyCheck (CRC) to control information. The CRC is masked by an Identifier(ID) known as a Radio Network Temporary Identifier (RNTI) according tothe owner or usage of the PDCCH. If the PDCCH is directed to a specificUE, its CRC may be masked by a cell-RNTI (C-RNTI) of the UE. If thePDCCH is for a paging message, the CRC of the PDCCH may be masked by aPaging Indicator Identifier (P-RNTI). If the PDCCH carries systeminformation, particularly, a System Information Block (SIB), its CRC maybe masked by a system information ID and a System Information RNTI(SI-RNTI). To indicate that the PDCCH carries a Random Access Responsein response to a Random Access Preamble transmitted by a UE, its CRC maybe masked by a Random Access-RNTI (RA-RNTI).

FIG. 4 illustrates the structure of an uplink subframe. An uplinksubframe may be divided into a control region and a data region in thefrequency domain. A Physical Uplink Control CHannel (PUCCH) carryinguplink control information is allocated to the control region and aPhysical Uplink Shared Channel (PUSCH) carrying user data is allocatedto the data region. To maintain the property of a single carrier, a UEdoes not transmit a PUSCH and a PUCCH simultaneously. A PUCCH for a UEis allocated to an RB pair in a subframe. The RBs of the RB pair occupydifferent subcarriers in two slots. Thus it is said that the RB pairallocated to the PUCCH is frequency-hopped over a slot boundary.

Reference Signals (RSs)

In a wireless communication system, a Packet is transmitted on a radiochannel. In view of the nature of the radio channel, the Packet may bedistorted during the transmission. To receive the signal successfully, areceiver should compensate for the distortion of the received signalusing channel information. Generally, to enable the receiver to acquirethe channel information, a transmitter transmits a signal known to boththe transmitter and the receiver and the receiver acquires knowledge ofchannel information based on the distortion of the signal received onthe radio channel. This signal is called a pilot signal or an RS.

In the case of data transmission and reception through multipleantennas, knowledge of channel states between Transmission (Tx) antennasand Reception (Rx) antennas is required for successful signal reception.Accordingly, an RS should be transmitted through each Tx antenna.

RSs may be divided into downlink RSs and uplink RSs. In the current LTEsystem, the uplink RSs include:

i) DeModulation-Reference Signal (DM-RS) used for channel estimation forcoherent demodulation of information delivered on a PUSCH and a PUCCH;and

ii) Sounding Reference Signal (SRS) used for an eNB or a network tomeasure the quality of an uplink channel in a different frequency.

The downlink RSs are categorized into:

i) Cell-specific Reference Signal (CRS) shared among all UEs of a cell;

ii) UE-specific RS dedicated to a specific UE;

iii) DM-RS used for coherent demodulation of a PDSCH, when the PDSCH istransmitted;

iv) Channel State Information-Reference Signal (CSI-RS) carrying CSI,when downlink DM-RSs are transmitted;

v) Multimedia Broadcast Single Frequency Network (MBSFN) RS used forcoherent demodulation of a signal transmitted in MBSFN mode; and

vi) positioning RS used to estimate geographical position informationabout a UE.

RSs may also be divided into two types according to their purposes: RSfor channel information acquisition and RS for data demodulation. Sinceits purpose lies in that a UE acquires downlink channel information, theformer should be transmitted in a broad band and received even by a UEthat does not receive downlink data in a specific subframe. This RS isalso used in a situation like handover. The latter is an RS that an eNBtransmits along with downlink data in specific resources. A UE candemodulate the data by measuring a channel using the RS. This RS shouldbe transmitted in a data transmission area.

Modeling of MIMO System

FIG. 5 is a diagram illustrating a configuration of a wirelesscommunication system having multiple antennas.

As shown in FIG. 5(a), if the number of transmit antennas is increasedto NT and the number of receive antennas is increased to NR, atheoretical channel transmission capacity is increased in proportion tothe number of antennas, unlike the case where a plurality of antennas isused in only a transmitter or a receiver. Accordingly, it is possible toimprove a transfer rate and to remarkably improve frequency efficiency.As the channel transmission capacity is increased, the transfer rate maybe theoretically increased by a product of a maximum transfer rate Roupon utilization of a single antenna and a rate increase ratio Ri.

R _(i)=min(N _(T) ,N _(R))  [Equation 1]

For instance, in an MIMO communication system, which uses 4 transmitantennas and 4 receive antennas, a transmission rate 4 times higher thanthat of a single antenna system can be obtained. Since this theoreticalcapacity increase of the MIMO system has been proved in the middle of90's, many ongoing efforts are made to various techniques tosubstantially improve a data transmission rate. In addition, thesetechniques are already adopted in part as standards for various wirelesscommunications such as 3G mobile communication, next generation wirelessLAN and the like.

The trends for the MIMO relevant studies are explained as follows. Firstof all, many ongoing efforts are made in various aspects to develop andresearch information theory study relevant to MIMO communicationcapacity calculations and the like in various channel configurations andmultiple access environments, radio channel measurement and modelderivation study for MIMO systems, spatiotemporal signal processingtechnique study for transmission reliability enhancement andtransmission rate improvement and the like.

In order to explain a communicating method in an MIMO system in detail,mathematical modeling can be represented as follows. It is assumed thatthere are NT transmit antennas and NR receive antennas.

Regarding a transmitted signal, if there are NT transmit antennas, themaximum number of pieces of information that can be transmitted is NT.Hence, the transmission information can be represented as shown inEquation 2.

S=└s ₁ ,s ₂ , . . . ,s _(N) _(T) ┘^(T)  [Equation 2]

Meanwhile, transmit powers can be set different from each other forindividual pieces of transmission information s₁, s₂, . . . , s_(N) _(T), respectively. If the transmit powers are set to P₁, P₂, . . . , P_(N)_(T) , respectively, the transmission information with adjusted transmitpowers can be represented as Equation 3.

ŝ=[ŝ ₁ ,ŝ ₂ , . . . ŝ _(N) _(T) ]^(T)=[P ₁ s ₁ ,P ₂ s _(e) , . . . ,P_(N) _(T) s _(n) _(T) ]^(T)  [Equation 3]

In addition, Ŝ can be represented as Equation 4 using diagonal matrix Pof the transmission power.

$\begin{matrix}{\hat{s} = {{\begin{bmatrix}P_{1} & \; & \; & 0 \\\; & P_{2} & \; & \; \\\; & \; & \ddots & \; \\0 & \; & \; & P_{N_{T}}\end{bmatrix}\begin{bmatrix}s_{1} \\s_{2} \\\vdots \\s_{N_{T}}\end{bmatrix}} = {Ps}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

Assuming a case of configuring NT transmitted signals x₁, x₂, . . . ,x_(N) _(T) , which are actually transmitted, by applying weight matrix Wto the information vector Ŝ having the adjusted transmit powers, theweight matrix W serves to appropriately distribute the transmissioninformation to each antenna according to a transport channel state. x₁,x₂, . . . , x_(N) _(T) can be expressed by using the vector X asfollows.

$\begin{matrix}{x = {\begin{bmatrix}x_{1} \\x_{2} \\\vdots \\x_{i} \\\vdots \\x_{N_{T}}\end{bmatrix} = {{\begin{bmatrix}w_{11} & w_{12} & \cdots & w_{1N_{T}} \\w_{21} & w_{22} & \cdots & w_{2N_{T}} \\\vdots & \; & \ddots & \; \\w_{i\; 1} & w_{i\; 2} & \cdots & w_{{iN}_{T}} \\\vdots & \; & \ddots & \; \\w_{N_{T}1} & w_{N_{T}2} & \cdots & w_{N_{T}N_{T}}\end{bmatrix}\begin{bmatrix}{\hat{s}}_{1} \\{\hat{s}}_{2} \\\vdots \\{\hat{s}}_{j} \\\vdots \\{\hat{s}}_{N_{T}}\end{bmatrix}} = {{W\hat{s}} = {WPs}}}}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack\end{matrix}$

In Equation 5, w_(ij) denotes a weight between an i^(th) transmitantenna and j^(th) information. W is also called a precoding matrix.

If the NR receive antennas are present, respective received signals y₁,y₂, . . . , y_(N) _(R) of the antennas can be expressed as follows.

y=[y ₁ ,y ₂ , . . . ,y _(N) _(R) ]^(T)  [Equation 6]

If channels are modeled in the MIMO wireless communication system, thechannels may be distinguished according to transmit/receive antennaindexes. A channel from the transmit antenna j to the receive antenna iis denoted by h_(ij). In h_(ij), it is noted that the indexes of thereceive antennas precede the indexes of the transmit antennas in view ofthe order of indexes.

FIG. 5(b) is a diagram illustrating channels from the NT transmitantennas to the receive antenna i. The channels may be combined andexpressed in the form of a vector and a matrix. In FIG. 5(b), thechannels from the NT transmit antennas to the receive antenna i can beexpressed as follows.

h _(i) ^(T)=[h _(i1) ,h _(i2) , . . . ,h _(iN) _(T) ]  [Equation 7]

Accordingly, all channels from the NT transmit antennas to the NRreceive antennas can be expressed as follows.

$\begin{matrix}{H = {\begin{bmatrix}h_{1}^{T} \\h_{2}^{T} \\\vdots \\h_{i}^{T} \\\vdots \\h_{N_{R}}^{T}\end{bmatrix} = \begin{bmatrix}h_{11} & h_{12} & \cdots & h_{1N_{T}} \\h_{21} & h_{22} & \cdots & h_{2N_{T}} \\\vdots & \; & \ddots & \; \\h_{i\; 1} & h_{i\; 2} & \cdots & h_{{iN}_{T}} \\\vdots & \; & \ddots & \; \\h_{N_{R^{1}}} & h_{N_{R^{2}}} & \cdots & h_{N_{R^{N_{T}}}}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 8} \right\rbrack\end{matrix}$

An AWGN (Additive White Gaussian Noise) is added to the actual channelsafter a channel matrix H. The AWGN n₁, n₂, . . . , n_(N) _(R)respectively added to the NR receive antennas can be expressed asfollows.

n=[n ₁ ,n ₂ , . . . ,n _(N) _(R) ]^(T)  [Equation 9]

Through the above-described mathematical modeling, the received signalscan be expressed as follows.

$\begin{matrix}{y = {\quad{\begin{bmatrix}y_{1} \\y_{2} \\\vdots \\y_{i} \\\vdots \\y_{N_{R}}\end{bmatrix} = {{{\begin{bmatrix}h_{11} & h_{12} & \cdots & h_{1N_{T}} \\h_{21} & h_{22} & \cdots & h_{2N_{T}} \\\vdots & \; & \ddots & \; \\h_{i\; 1} & h_{i\; 2} & \cdots & h_{{iN}_{T}} \\\vdots & \; & \ddots & \; \\h_{N_{R}1} & h_{N_{R}2} & \cdots & h_{N_{R}N_{T}}\end{bmatrix}\begin{bmatrix}x_{1} \\x_{2} \\\vdots \\x_{j} \\\vdots \\x_{N_{T}}\end{bmatrix}} + \begin{bmatrix}n_{1} \\n_{2} \\\vdots \\n_{i} \\\vdots \\n_{N_{R}}\end{bmatrix}} = {{Hx} + n}}}}} & \left\lbrack {{Equation}\mspace{14mu} 10} \right\rbrack\end{matrix}$

Meanwhile, the number of rows and columns of the channel matrix Hindicating the channel state is determined by the number of transmit andreceive antennas. The number of rows of the channel matrix H is equal tothe number NR of receive antennas and the number of columns thereof isequal to the number NR of transmit antennas. That is, the channel matrixH is an NR×NT matrix.

The rank of the matrix is defined by the smaller of the number of rowsand the number of columns, which are independent from each other.Accordingly, the rank of the matrix is not greater than the number ofrows or columns. The rank rank(H) of the channel matrix H is restrictedas follows.

rank(H)≤min(N _(T) ,N _(R))  [Equation 11]

Additionally, the rank of a matrix can also be defined as the number ofnon-zero Eigen values when the matrix is Eigen-value-decomposed.Similarly, the rank of a matrix can be defined as the number of non-zerosingular values when the matrix is singular-value-decomposed.Accordingly, the physical meaning of the rank of a channel matrix can bethe maximum number of channels through which different pieces ofinformation can be transmitted.

In the description of the present document, ‘rank’ for MIMO transmissionindicates the number of paths capable of sending signals independentlyon specific time and frequency resources and ‘number of layers’indicates the number of signal streams transmitted through therespective paths. Generally, since a transmitting end transmits thenumber of layers corresponding to the rank number, one rank has the samemeaning of the layer number unless mentioned specially.

Synchronization Acquisition of D2D UE

Now, a description will be given of synchronization acquisition betweenUEs in D2D communication based on the foregoing description in thecontext of the legacy LTE/LTE-A system. In an OFDM system, iftime/frequency synchronization is not acquired, the resulting Inter-CellInterference (ICI) may make it impossible to multiplex different UEs inan OFDM signal. If each individual D2D UE acquires synchronization bytransmitting and receiving a synchronization signal directly, this isinefficient. In a distributed node system such as a D2D communicationsystem, therefore, a specific node may transmit a representativesynchronization signal and the other UEs may acquire synchronizationusing the representative synchronization signal. In other words, somenodes (which may be an eNB, a UE, and a Synchronization Reference Node(SRN, also referred to as a synchronization source)) may transmit a D2DSynchronization Signal (D2DSS) and the remaining UEs may transmit andreceive signals in synchronization with the D2DSS.

D2DSSs may include a Primary D2DSS (PD2DSS) or a Primary SidelinkSynchronization Signal (PSSS) and a Secondary D2DSS (SD2DSS) or aSecondary Sidelink Synchronization Signal (SSSS). The PD2DSS may beconfigured to have a similar/modified/repeated structure of a Zadoff-chusequence of a predetermined length or a Primary Synchronization Signal(PSS). Unlike a DL PSS, the PD2DSS may use a different Zadoff-chu rootindex (e.g., 26, 37). And, the SD2DSS may be configured to have asimilar/modified/repeated structure of an M-sequence or a SecondarySynchronization Signal (SSS). If UEs synchronize their timing with aneNB, the eNB serves as an SRN and the D2DSS is a PSS/SSS. Unlike PSS/SSSof DL, the PD2DSS/SD2DSS follows UL subcarrier mapping scheme. FIG. 6shows a subframe in which a D2D synchronization signal is transmitted. APhysical D2D Synchronization Channel (PD2DSCH) may be a (broadcast)channel carrying basic (system) information that a UE should firstobtain before D2D signal transmission and reception (e.g., D2DSS-relatedinformation, a Duplex Mode (DM), a TDD UL/DL configuration, a resourcepool-related information, the type of an application related to theD2DSS, etc.). The PD2DSCH may be transmitted in the same subframe as theD2DSS or in a subframe subsequent to the frame carrying the D2DSS. ADMRS can be used to demodulate the PD2DSCH.

The SRN may be a node that transmits a D2DSS and a PD2DSCH. The D2DSSmay be a specific sequence and the PD2DSCH may be a sequencerepresenting specific information or a codeword produced bypredetermined channel coding. The SRN may be an eNB or a specific D2DUE. In the case of partial network coverage or out of network coverage,the SRN may be a UE.

In a situation illustrated in FIG. 7, a D2DSS may be relayed for D2Dcommunication with an out-of-coverage UE. The D2DSS may be relayed overmultiple hops. The following description is given with the appreciationthat relay of an SS covers transmission of a D2DSS in a separate formataccording to a SS reception time as well as direct Amplify-and-Forward(AF)-relay of an SS transmitted by an eNB. As the D2DSS is relayed, anin-coverage UE may communicate directly with an out-of-coverage UE.

D2D Resource Pool

FIG. 8 shows an example of a UE1, a UE2 and a resource pool used by theUE1 and the UE2 performing D2D communication. In FIG. 8 (a), a UEcorresponds to a terminal or such a network device as an eNBtransmitting and receiving a signal according to a D2D communicationscheme. A UE selects a resource unit corresponding to a specificresource from a resource pool corresponding to a set of resources andthe UE transmits a D2D signal using the selected resource unit. A UE2corresponding to a reception UE receives a configuration of a resourcepool in which the UE1 is able to transmit a signal and detects a signalof the UE1 in the resource pool. In this case, if the UE1 is located atthe inside of coverage of an eNB, the eNB can inform the UE1 of theresource pool. If the UE1 is located at the outside of coverage of theeNB, the resource pool can be informed by a different UE or can bedetermined by a predetermined resource. In general, a resource poolincludes a plurality of resource units. A UE selects one or moreresource units from among a plurality of the resource units and may beable to use the selected resource unit(s) for D2D signal transmission.FIG. 8 (b) shows an example of configuring a resource unit. Referring toFIG. 8 (b), the entire frequency resources are divided into the NFnumber of resource units and the entire time resources are divided intothe NT number of resource units. In particular, it is able to defineN_(F)*N_(T) number of resource units in total. In particular, a resourcepool can be repeated with a period of N_(T) subframes. Specifically, asshown in FIG. 8, one resource unit may periodically and repeatedlyappear. Or, an index of a physical resource unit to which a logicalresource unit is mapped may change with a predetermined patternaccording to time to obtain a diversity gain in time domain and/orfrequency domain. In this resource unit structure, a resource pool maycorrespond to a set of resource units capable of being used by a UEintending to transmit a D2D signal.

A resource pool can be classified into various types. First of all, theresource pool can be classified according to contents of a D2D signaltransmitted via each resource pool. For example, the contents of the D2Dsignal can be classified into various signals and a separate resourcepool can be configured according to each of the contents. The contentsof the D2D signal may include SA (scheduling assignment), a D2D datachannel, and a discovery channel. The SA may correspond to a signalincluding information on a resource position of a D2D data channel,information on MCS (modulation and coding scheme) necessary formodulating and demodulating a data channel, information on a MIMOtransmission scheme, information on TA (timing advance), and the like.The SA signal can be transmitted on an identical resource unit in amanner of being multiplexed with D2D data. In this case, an SA resourcepool may correspond to a pool of resources that an SA and D2D data aretransmitted in a manner of being multiplexed. The SA signal can also bereferred to as a D2D control channel or a PSCCH (physical sidelinkcontrol channel). The D2D data channel (or, PSSCH (physical sidelinkshared channel)) corresponds to a resource pool used by a transmissionUE to transmit user data. If an SA and a D2D data are transmitted in amanner of being multiplexed in an identical resource unit, D2D datachannel except SA information can be transmitted only in a resource poolfor the D2D data channel. In other word, resource elements (REs), whichare used to transmit SA information in a specific resource unit of an SAresource pool, can also be used for transmitting D2D data in a D2D datachannel resource pool. The discovery channel may correspond to aresource pool for a message that enables a neighboring UE to discovertransmission UE transmitting information such as ID of the UE, and thelike.

Although contents of D2D signal are identical to each other, it may usea different resource pool according to a transmission/receptionattribute of the D2D signal. For example, in case of the same D2D datachannel or the same discovery message, the D2D data channel or thediscovery signal can be classified into a different resource poolaccording to a transmission timing determination scheme (e.g., whether aD2D signal is transmitted at the time of receiving a synchronizationreference signal or the timing to which a prescribed timing advance isadded) of a D2D signal, a resource allocation scheme (e.g., whether atransmission resource of an individual signal is designated by an eNB oran individual transmission UE selects an individual signal transmissionresource from a pool), a signal format (e.g., number of symbols occupiedby a D2D signal in a subframe, number of subframes used for transmittinga D2D signal), signal strength from an eNB, strength of transmit powerof a D2D UE, and the like. For clarity, a method for an eNB to directlydesignate a transmission resource of a D2D transmission UE is referredto as a mode 1. If a transmission resource region is configured inadvance or an eNB designates the transmission resource region and a UEdirectly selects a transmission resource from the transmission resourceregion, it is referred to as a mode 2. In case of performing D2Ddiscovery, if an eNB directly indicates a resource, it is referred to asa type 2. If a UE directly selects a transmission resource from apredetermined resource region or a resource region indicated by the eNB,it is referred to as a type 1.

Transmission and Reception of SA

A mode 1 UE can transmit an SA signal (or, a D2D control signal, SCI(sidelink control information)) via a resource configured by an eNB. Amode 2 UE receives a configured resource to be used for D2Dtransmission. The mode 2 UE can transmit SA by selecting a timefrequency resource from the configured resource.

The SA period can be defined as FIG. 9. Referring to FIG. 9, a first SAperiod can start at a subframe apart from a specific system frame asmuch as a prescribed offset (SAOffsetIndicator) indicated by higherlayer signaling. Each SA period can include an SA resource pool and asubframe pool for transmitting D2D data. The SA resource pool caninclude subframes ranging from a first subframe of an SA period to thelast subframe among subframes indicated by a subframe bitmap(saSubframeBitmap) to transmit SA. In case of mode 1, T-RPT(time-resource pattern for transmission) is applied to the resource poolfor transmitting D2D data to determine a subframe in which an actualdata is transmitted. As shown in the drawing, if the number of subframesincluded in an SA period except the SA resource pool is greater than thenumber of T-RPT bits, the T-RPT can be repeatedly applied and the lastlyapplied T-RPT can be applied in a manner of being truncated as many asthe number of remaining subframes. A transmission UE performstransmission at a position where a T-RPT bitmap corresponds to 1 in anindicated T-RPT and 4 transmissions are performed in a MAC PDU.

In the following, when a control signal and data are transmitted in thesame subframe, a method of transmitting a control signal and data isexplained. According to the method, it may be able to reduce inter-UEinterference while diversity of the control signal is obtained.Moreover, it may be able to reduce PARR as well. In the followingdescription, a control signal and a scheduling signal are referred to ascontrol information (CI). All or a part of information fortransmitting/receiving data such as MCS, resource allocation, Tx power,NDI (new data indicator), RV (redundancy version), retransmissionnumber, CQO, PMI, etc. can be transmitted in a manner of being includedin the CI.

Message Transmission Structure, Transmission Method

According to one embodiment of the present invention, when a message istransmitted, a format (including an RB size of SA) for transmitting SA,a location at which SA is transmitted, a scheme, an SA poolconfiguration, and the like can be differentiated according to a type ofthe message, a type of a E transmitting the message, or an transmittedBR size.

As a specific example, a scheme of multiplexing control information (SA)with a data may vary according to a message size. In particular, if asize of a message is greater than a predetermined value, controlinformation for the message and the message are transmitted (i.e., TDMtransmission) in resources distinguished from each other on a time axis.If the size of the message is less than the predetermined value, thecontrol information for the message and the message can be transmitted(i.e., FDM transmission) in resources distinguished from each other on afrequency axis.

In this case, the message greater than the predetermined valuecorresponds to a periodic message and the message less than thepredetermined value may correspond to an event triggered message. Inparticular, when a periodic message is transmitted, the periodic messageis transmitted using a scheme of performing TDM on SA and data. When anevent triggered message is transmitted, the event triggered message canbe transmitted using a scheme of performing FDM on SA and data.

In this case, if a message of a large size (periodic message) istransmitted on a wide band and a message of a small size is transmittedon a narrow band (e.g., 1 RB), although a different multiplexing schemeis used, the loss is insignificant in terms of CM/PAPR. Specifically,referring to FIGS. 10 and 11, (multi cluster SC-FDM) cubic metric iscompared with OFDM and single cluster SC-FDM when a message of a largesize (or, a periodic message) is transmitted via 40 RBs and a message ofa small size (or, an event triggered message) is transmitted via 1 RB.As shown in the drawings, although multi cluster SC-FDM transmission isperformed while a multiplexing scheme is changed, it is able to see thata cubic metric (CM) value has almost no difference with the SC-FDM case.In particular, although narrow band transmission such as a controlsignal and wideband data transmission are performed at the same time, CMis not considerably increased. On the other hand, when a TDM scheme andan FDM scheme are used together, in some cases, if a message intends tosecure large coverage of SA, the SA is transmitted in a manner of beingTDMed with data. Otherwise, the SA and the data are transmitted in amanner of being FDMed to mitigate a half-duplex problem. In particular,if whether to transmit the SA and the data at the same time is flexiblydetermined according to a situation, it may be able to enhance systemperformance, message forwarding performance of a transmission UE,interference avoidance performance, and the like. More specifically, ifthe SA and the data are transmitted in a manner of being TDMed, thecoverage of the SA can be widened. As a result, the number of UEsdecoding the SA of a corresponding UE increases. In particular, since itis able to avoid a connected data resource after the decoding,interference avoidance performance can be enhanced.

When a multiplexing scheme is differently used according to a size, atype, and the like of a message, FIGS. 12 and 13 illustrate an exampleof an available resource structure/resource allocation. Yet, anavailable resource structure is not restricted to the resource structureshown in FIGS. 12 and 13. Various resource structures rather than theresource structure shown in FIGS. 12 and 13 can be used if the resourcestructures are matched with the aforementioned contents.

Meanwhile, in the foregoing description, a message of a small size (or,an event triggered message) can be transmitted using an FDM scheme. Inthis case, schemes described in the following can be used as the FDMscheme. Of course, each of various resource structures/allocationschemes described in the following can configure an independentembodiment.

Referring to FIG. 14, CI candidate regions are determined in advance andCI is transmitted from one of the CI candidate regions. When controlinformation and a message are transmitted in resources distinguishedfrom each other on a frequency axis, control information for a messageis transmitted in at least one or more regions among a plurality ofcandidate regions configured in advance. To this end, a partial resourceregion separated from a frequency domain is preconfigured as a regioncapable of transmitting CI and Rx UEs can perform blind decoding on theCI in the region. In this case, a preconfigured candidate region mayinclude slots on a time axis and the predetermined number of RBs on afrequency axis.

A position of a candidate region in which control information isincluded in a second slot can be restricted by a position of a candidateregion in which control information is included in a first slot. Forexample, CI of a second slot can be transmitted in i) a CI regionincluded within +/−N1 RB, ii) a region within +N2 RB, or iii) a regionwithin −N3 RB on the basis of a CI position in a first slot. In thiscase, the N1, the N2, and the N3 may correspond to predetermined values.The regions mentioned earlier in i) to iii) can be differentlydetermined depending on a position of CI in the first slot. In order tosatisfy single carrier property in SC-FDMA scheme, it is necessary forthe regions to be contiguous each other in frequency domain. Hence, itmay be able to set a limit on a CI position of the second slot.

In this case, a position at which data is transmitted can beindependently configured irrespective of CI or can be determined in amanner of being interlocked with a position of the CI. The CI may or maynot explicitly indicate RA of data.

In order to prevent a UE from performing data decoding (or, blinddecoding) in a region considerably deviated from a position at which CIis actually transmitted, it may apply at least one rule among rules a)to d) described in the following.

a) Data is not transmitted in a frequency resource position at which CIis transmitted.

b) Data can be transmitted in i) a region within +/−K1 RB, ii) a regionwithin +K2 RB, or iii) a region within −K3 RB in an RB in which CI istransmitted. In this case, the K1, the K2, and the K3 may correspond topredetermined values. The conditions (i to iii) can be differentlyapplied depending on a position at which CI is transmitted. This rule isapplied to prevent a case that CI and data are transmitted in a mannerof being considerably apart from each other. For example, it may be ableto determine a rule that data is to be continuously transmitted in RBindexes only in +direction on the basis of a position at which CI istransmitted. If the rule is applied, an Rx UE can implicitly identify astart RB of a position at which data is transmitted through the positionat which the CI is transmitted. In the aspect of a Tx UE, when a UEdetermines a position at which data is transmitted, it may be able todetermine a rule that CI is to be transmitted in a lowest RB index inthe position at which the data is transmitted (of course, the RBcorresponds to an RB configured to transmit the CI).

c) CI of a second slot is not transmitted at a frequency positionidentical to a CI position of a first slot.

d) CI is not located in the middle of a data RB. Or, a center RB of theentire frequency band is not included in a plurality of thepreconfigured candidate regions. This rule is applied to prevent PAPRfrom being excessively increased by setting a limit on the number ofclusters to 3 although CI and data generate an independent SC-FDMsignal.

An Rx UE may not perform data decoding in a region in which data is nottransmitted in consideration of at least one of a) to d).

Subsequently, CI of a first slot and CI of a second slot can beindependently determined. In this case, it may be able to determine arule that a case of transmitting CI at the same frequency position ofthe two slots is to be excluded in advance. In particular, a candidateregion in which control information is included in the second slot and acandidate region in which control information is included in the firstslot can be positioned at a different frequency band. A UE may performblind decoding on CI in the first slot and the second slot,respectively. In this case, in order to prevent excessive blinddecoding, it may be able to set a limit on the number of candidate CIsaccording to a slot. For example, when BD is performed as many as anumber equal to or less than X times in each subframe, the maximum CInumber according to a slot can be determined by floor (sqrt (X)).

In the foregoing description, if two or more RSs are deployed to asingle slot, slot hopping can be applied to data as well. In this case,the rule b) can be independently applied according to a slot.

Subsequently, FIGS. 15 to 17 illustrate a method of transmitting a V2Xchannel by reusing a slot hopping structure similar to PUCCH and a PUSCHstructure. In this case, it is preferable to transmit CI and data in amanner of making the CI and the data to be adjacent to each other toreduce in-band emission to a different UE. More specifically, it may beable to reduce an in-band emission component (EVM shoulder) which occursnear an allocated RB.

Specifically, CI is deployed while hopping between slots and data isdeployed between CIs. In particular, CIs are adjacent to each other infrequency domain and a position at which CI is transmitted is changedaccording to a slot. CI and/or data can be transmitted using a legacyPUCCH structure or a PUSCH structure. For example, CI uses 2 RSs perslot similar to a PUCCH format 2/3 and data uses 1 RS per slot similarto a PUSCH. CI and/or data can be transmitted using a legacy PSCCHstructure or a PSSCH structure. Or, CI and/or data can be transmittedusing a modified PSCCH/PSSCH structure (puncturing or rate matching isperformed on the last symbol). In this case, puncturing is performed ona partial symbol only instead of the whole of the last symbol. Or, inorder to cope with high mobility, a DMRS can be additionally deployed.

In this case, an Rx UE performs blind decoding on CI in each slot toidentify a position of data. When RA information is explicitly includedin CI, if a UE performs blind decoding on a position of the CI, a finalconfirm can be performed via CI contents. When CI is transmittedaccording to a slot, the CI can be transmitted in a form that the sameRV is repeated. Similar to incremental redundancy, a different RV can betransmitted according to a slot (e.g., first slot RV 0, second slot RV1). In this case, a data RE can be mapped using one of three methodsdescribed in the following.

As a first method, encoding and modulation symbols are mapped to 2 slotsexcept a CI region according to a determined RB size. When data isactually mapped to an RE, the data is mapped in a manner of beingshifted as many as RBs (or, a group of REs, when CI fails to fill aspecific RB) occupied by the CI region according to a slot. In otherword, data generates a codeword under the assumption that there is no CIand the data is mapped in a manner of shifting a first slot or a secondslot as much as a region occupied by CI in a subframe in which the CI istransmitted. FIG. 15 illustrates the abovementioned mapping method. Themapping method corresponds to a method of dynamically changing a data REaccording to whether or not CI is transmitted.

As a second method, as shown in FIG. 16, a data RE is mapped until a CIregion. If CI is transmitted, it may perform rate matching on a CI part.According to the present method, a codeword is generated inconsideration of a case of not transmitting CI in every subframe. Then,rate matching is performed on a CI region in a subframe in which CI istransmitted. The present method has a merit in that an RB size is thesame irrespective of whether or not CI is transmitted.

As a third method, as shown in FIG. 17, data is mapped in the samefrequency position during 2 slots and CI can be mapped to a positionnear an RB in which the data is transmitted. The present method has amerit in that it may have data codeword to RE mapping irrespective ofwhether or not CI is transmitted. Yet, since the CI is transmitted to aposition near a data region, an effective RB size may change.

According to the aforementioned three methods, although CI is deployedat the top in a first slot (CI is deployed at a side where an RB indexis high), an opposite case is available as well. In particular, CI canbe deployed at the bottom in the first slot and CI can be deployed atthe top in a second slot.

Meanwhile, the slot hopping scheme of the CI can be applied in a mannerthat a slot is hopped in an SA pool in a legacy D2D operation. Inparticular, according to 3GPP Rel. 12/13, SA performs transmission twotimes in each SA pool. In this case, due to a half-duplex constraint, itmay be able to receive one transmission only among the two SAtransmissions. In this case, since it is unable to obtain a frequencydiversity gain, SA reception performance can be considerably degraded.In this case, if slot hopping is permitted, since it is able to obtainthe frequency diversity gain, a probability of receiving SA can beenhanced. FIG. 18 illustrates an embodiment of performing SA slothopping. A slot hopping operation of the SA can be configured by anetwork. Or, whether a slot hopping is enabled or disabled can bedetermined in advance. When an in-coverage UE has a small frequencyoffset, a UE has a small frequency offset due to a low speed of the UE(e.g., a pedestrian UE), or a big frequency offset or Doppler shiftoccurs, the slot hopping operation can be selectively applied to a casethat two or more DMRSs of SA are deployed according to a slot.

FIGS. 19 and 20 illustrate an example for a scheme of independentlytransmitting CI and data. In particular, CI is deployed at an edge of abandwidth and data is deployed at a region in which data is transmittedtogether with PUSCH. In this case, a region in which the CI istransmitted and a region in which the data is transmitted can bedetermined in advance or can be signaled by a network via physical layersignaling or higher layer signaling. FIG. 19 illustrates an embodimentfor the present scheme. Or, as shown in FIG. 20, it may not apply slothopping while diversity of control is obtained. This method can beapplied when 3-cluster transmission is available but PAPR increase isnot that big due to a small size of an RB size of a control region. Inthis case, CI, which is transmitted in a manner of being separated infrequency domain, can include the same information. In this case, the CIcan be transmitted by applying separate DFT precoding to the CI. Or, theCI can be transmitted by applying single DFT precoding to the CI in aform of being separated in frequency domain only. When the CI isseparated from frequency domain in a CI region, a frequency domainoffset can be applied to the CI. In this case, a frequency domain offsetof the same size can be applied to all CI resources. Hence, although aCI resource is transmitted at any CI region, it may be able to make theCI resource have the same frequency domain diversity.

Subsequently, FIGS. 21 to 23 illustrate a scheme of configuring a poolof an event triggered message and an SA pool in the same subframe. Inthis case, if SA of a periodic message and data are TDMed and a pool ofthe SA is configured by a size for solving HDC, as shown in FIG. 17, itmay solve a problem of wasting a frequency resource of the SA pool.Specifically, a partial SA resource of the SA pool can be reserved forthe usage of transmitting an event triggered message or a UEtransmitting an event triggered message may select an SA resource totransmit the event triggered message. When the partial SA resource ofthe SA pool is reserved for the event triggered message, the partial SAresource of the SA pool can be randomly determined in every period. Or,the partial SA resource of the SA pool can be determined by a hoppingpattern, which is determined by a specific ID or a parameter indicatedby a network via higher layer signaling. Or, it may be able to partlyconfigure an SA pool for an event triggered message irrespective of anSA pool for a periodic message. Or, in case of implicitly transmittingan event triggered message, a periodic message is not transmitted in acorresponding SA period. In this case, the event triggered message canbe indicated using legacy SA. In this case, application of T-RPT isexcluded and data is transmitted in a subframe in which SA istransmitted. Frequency RA and MCS can be indicated via SA. Or, RA of anevent triggered message is determined in a manner of being dependent ona fixed or SA pool size (e.g., remaining frequency region of SA pool ora part of the remaining frequency region corresponds to an eventtriggered message transmission size). In this case, MCS can betransmitted in a piggyback form.

Contents Included in Control Information

In the following, contents included in SA are explained.

An ID and a source (group) ID field can be included in SA. This fieldcan be used as a seed value that enables a UE to have a differenthopping pattern according to a source for T-RPT randomization. Or, theID can be originated from a destination ID of a higher layer. In thiscase, since a scheme of selecting an ID included in the SA is differentaccording to a UE, an ID can be included in the SA in a manner that atransmission UE generates a different ID.

An ID may not be included in SA contents to reduce a bit field of theSA. In this case, all or a part of a DMRS base sequence, CS (cyclicshift), OCC, and a scrambling sequence can be determined using adifferent field rather than the ID. In this case, all or a part of RA,MCS, a priority level, a next reservation section length (a position ofa resource to be transmitted next on the basis of a current transmissionresource), a timing offset between SA and data, T-RPT, a retransmissionnumber, and the like can be utilized. For example, the RA field can beused for generating an RS/scrambling sequence. In this case, there is apossibility that UEs using the same resource use the same RS. Hence, itmay differently configure CS and/or OCC using a different field (all ora part of MCS, priority level, reservation section length, etc.) to makeRSs to be orthogonal to each other.

Or, when the ID is included in the SA, the ID can be transmitted with areduced length. In this case, since the ID length is not sufficient, acollision may occur between an RS and a scrambling sequence. Hence, theRS/scrambling sequence can be generated using all or a part of the IDfield. Or, the ID can be transmitted in a manner of being masked by aCRC field without being explicitly transmitted. In this case, it maydetermine a rule that combining is performed on the same SA ID (or, CRCID) only. Meanwhile, for example, a CRC field can be masked with apredetermined ID and an RS/scrambling sequence can be generated usingthe CRC field itself. And, an RS/scrambling sequence generated for datacan be determined using all or a part of fields transmitted to a CRC IDand/or SA. In other word, the RS/scrambling sequence of data isgenerated using a ‘predetermined partial filed’ included in the SA (afield to be used for generating the RS/scrambling sequence of datashould be determined in advance.). In this case, a CRC field can beappropriately used for generating the RS/scrambling sequence of data.The CRC field is differently generated according to information of adifferent field included in the SA. The CRC field can be used forchecking whether or not there is an error in data. In this case, if theSA includes contents different from each other, CRC fields of UEs mayvary. In particular, each of UEs can differently generate anRS/scrambling sequence of data using a different CRC field. As adifferent embodiment, while a partial ID is explicitly included, theremaining ID can be transmitted in a manner of being masked with a CRC(or, using a partial bit sequence of a CRC field). In this case, it maybe able to determine a rule that an RS sequence/scrambling sequence ofdata is generated using all or a part of an explicit ID, an ID maskedwith a CRC (or, a CRC field itself), and a field transmitted in a mannerof being included in SA. Or, an RS sequence and a scrambling sequencecan be generated using all or a part of an ID and a specific fieldincluded in SA. In this case, although it is able to use the ID todistinguish UEs from each other, the ID may also provide a help to areception UE when the reception UE performs a HARQ combining operation.According to a legacy LTE release 12/13 D2D, a DMRS sequence/scramblingsequence is generated using an ID included in 8-bit SA. In order toperform an additional randomization operation, a DMRS sequence and ascrambling sequence can be generated using ID N bits and M bits of adifferent field. For example, a DMRS sequence and a scrambling sequencecan be generated by combining an ID of 8 bits with 8 bits of a differentfield included in SA.

A UE type field can be included in the SA. Specifically, informationindicating a P-UE, a V-UE, or an RSU can be included in the SA. If apool is divided, the information may not be included in the SA. Yet,when cellular timing is different from GPS timing or timing is differentbetween cells while using the cellular timing, if overlap occurs betweenpools, the information can be included in the SA.

A priority level field (a message type or a message size) can beincluded in the SA. If an SA pool is divided, the priority level filedmay not be included in the SA.

MCS can be included in an SA field. In this case, 64QAM can be excludedfrom an MCS value. Since it is not necessary for UEs to implement 64QAM,UE implementation can be simplified. Yet, in order to improveperformance between links in future sidelink (D2D) communication, 64QAMcan be included in the MCS.

A hopping flag can be included in the SA field. Since the hopping flagis included in a legacy SA field, it is regarded as the hopping flag isnecessary. However, if wideband transmission is performed, since thehopping flag field is unable to obtain performance gain, the hoppingflag field can be used as a different usage. For example, when a messageof a big size is transmitted by combining event triggered messages or aplurality of messages or an RB size is equal to or greater than aprescribed threshold, the hopping flag field can be used for designatingdifferent information. For example, when a transmitted messagecorresponds to an event triggered message, the hopping flag field can beused as an indicator indicating wideband transmission or a message forforwarding a plurality of narrow band signals (e.g., by RSU). Or, whenSA is transmitted in every data transmission or SA indicates a HARQprocess number and RV of data, if a resource is selected via separatesensing according to each transmission, it may not apply frequencyhopping. In this case, it may not transmit a hopping flag in the SA.

A slot hopping flag field can be included in the SA. The slot hoppingflag field corresponds to a field for indicating whether or not slothopping of data is performed. The slot hopping flag field can beconfigured by a network. If the slot hopping flag field ispreconfigured, the slot hopping flag field may not be included in theSA.

An RA (resource allocation) field can be included in the SA.

In relation to RA information on a frequency axis, an RA bit size can bereduced according to the number of subchannels. For example, when afrequency resource is divided into the N number of subchannels, if it isassumed that overlap is prohibited between subchannels, bits as many asceil (log 2(N*(N+1)/2)) are necessary. In particular, it may have amerit in that it is able to reduce the number of bits in an RA field ina legacy RB unit. If data and SA are FDMed, in particular, if SA anddata are continuously FDMed, a start frequency position can be indicatedby a positon of the SA. Hence, it may be able to reduce more bits. Forexample, if a position of an end RB is indicated only and a frequencyresource is divided into subchannels, an RA field as much as ceil(log2(N)) is required only. Meanwhile, since a method of reducing the RAfield is able to perform various RAs, similar to a legacy method, themethod can be indicated in a unit of RB. In order to make UEs perform acommon operation in a specific operation, resource allocation can beperformed in an RB unit. Yet, a practically used resource can beallocated in a unit of a specific subchannel. A network can signal aresource allocation unit to UEs via physical layer signaling or higherlayer signaling. The abovementioned operation can be used not only for aresource allocation operation but also for an energy sensing operationor a resource reselection operation. In particular, a resourceselection/reselection/sensing operation can be performed in a resourceunit signaled by the network.

If continuous transmission is assumed in relation to RA information on atime axis, a bit size can be reduced. Yet, T-RPT bit can be used similarto a legacy method. In this case, in order to make each UE have adifferent hopping pattern, it may add a randomization seed value. If theaforementioned ID field is not used, it may add a separate T-RPTrandomization field. It may indicate a repetition number per MAC PDUonly or it may indicate (total transmission opportunity+repetitionnumber per MAC PDU). All or a part of 1, 2, 4, 8, and 16 can beindicated as a repetition number. Or, a field indicating the number ofSA periods during which SA is maintained, a field indicating the timingat which an RA of SA is applied, and a field indicating the timing (or,SA period) at which T-RPT starts can be included. Or, the number of MACPDUs transmitted via SA can be included.

Meanwhile, RS sequence hopping can be used for SA or data. In this case,current RS hopping is configured to be changed according to a slot. Ifthe number of RSs in a subframe/TTI exceeds 2, sequence hopping may varyaccording to an RS or a slot. If the sequence hopping varies accordingto an RS, a different sequence is used according to an adjacent RS. Ifthe sequence hopping varies according to a slot, an RS included in aslot uses the same base sequence. In the latter case, since the samesequence is transmitted within a slot, if a frequency offset is big, itis able to assume that the same sequence is transmitted in the same slotwhen interpolation is performed between RSs, thereby increasingperformance. In the former case, since a different RS sequence is used,if a frequency offset including a very big sequence occurs, the sequenceis randomized. Hence, it may have a merit in that an impact of ICIwithin a symbol is relatively cancelled. Meanwhile, the abovementionedRS hopping scheme or information on whether or not hopping is performedcan be differently configured according to a sidelink channel. Forexample, in case of SA, it may be able to configure an RS sequence to behopped between slots. In case of data, it may vary (hop) according to anRS sequence. In case of data, a seed ID for sequence hopping can beindicated by the SA.

Information indicating eNB timing or GNSS timing can be included inPSBCH contents or a PSSID. Or, SA can be transmitted with the GNSStiming and data can be transmitted with the eNB timing in the incoverage (DL timing or UL timing). In this case, an offset between theGNSS timing and the eNB timing can be signaled by including the offsetin the SA.

A reserved bit can be included in the SA field. For example, when across carrier operation is performed, a carrier indication fieldindicating a carrier on which data is transmitted after SA transmissioncan be included in the SA. Or, a reserved field can be included in theSA for a field indicating a carrier on which RV is transmitted andretransmission is performed after SA transmission. A length of thereserved bit included in the SA can be determined in advance or can besignaled by a network via physical layer signaling or higher layersignaling.

TA is not included in the SA. In case of a mode 1 (or, an eNB-basedscheduling mode), since transmission is performed with DL timing or GNSStiming and a TA bit field size corresponding to 11 bits is relativelybig, it may be preferable to exclude the TA field from the SA to securea coding rate. In case of the mode 1, when a UE performs transmissionwith reference to the GNSS timing, it is not necessary for the UE tohave the TA field. Yet, if a UE uses cellular timing and the mode 1, theTA field can be included in the SA. For any other cases, the TA field isnot used or can be set to all zeros. In particular, in case of using themode 1, if transmission is performed with reference to the GNSS timing,the TA field is not used or is set to all zeros. As an exceptionaloperation in the mode 1, a timing reference (GNSS or eNB) can beconfigured in advance according to an SA resource pool to determinewhether or not a UE uses the GNSS timing. If an SLSS ID of SLSSassociated with an SA pool uses a resource reserved for the GNSS, a UEis able to know that a signal received in the SA pool does not use theTA field although a mode corresponds to the mode 1.

Examples for the aforementioned proposed methods can also be included asone of implementation methods of the present invention. Hence, it isapparent that the examples are regarded as a sort of proposed schemes.The aforementioned proposed schemes can be independently implemented orcan be implemented in a combined (aggregated) form of a part of theproposed schemes. It may be able to configure an eNB to inform a UE ofinformation on whether to apply the proposed methods (information onrules of the proposed methods) via a predefined signal (e.g., physicallayer signal or upper layer signal).

Configurations of Devices for Embodiments of the Present Invention

FIG. 24 is a diagram for configurations of a transmitter and a receiver.

Referring to FIG. 24, a transmit point apparatus 10 may include areceive module 11, a transmit module 12, a processor 13, a memory 14,and a plurality of antennas 15. The antennas 15 represent the transmitpoint apparatus that supports MIMO transmission and reception. Thereceive module 11 may receive various signals, data and information froma UE on an uplink. The transmit module 12 may transmit various signals,data and information to a UE on a downlink. The processor 13 may controloverall operation of the transmit point apparatus 10.

The processor 13 of the transmit point apparatus 10 according to oneembodiment of the present invention may perform processes necessary forthe embodiments described above.

Additionally, the processor 13 of the transmit point apparatus 10 mayfunction to operationally process information received by the transmitpoint apparatus 10 or information to be transmitted from the transmitpoint apparatus 10, and the memory 14, which may be replaced with anelement such as a buffer (not shown), may store the processedinformation for a predetermined time.

Referring to FIG. 24, a UE 20 may include a receive module 21, atransmit module 22, a processor 23, a memory 24, and a plurality ofantennas 25. The antennas 25 represent the UE that supports MIMOtransmission and reception. The receive module 21 may receive varioussignals, data and information from an eNB on a downlink. The transmitmodule 22 may transmit various signals, data and information to an eNBon an uplink. The processor 23 may control overall operation of the UE20.

The processor 23 of the UE 20 according to one embodiment of the presentinvention may perform processes necessary for the embodiments describedabove.

Additionally, the processor 23 of the UE 20 may function tooperationally process information received by the UE 20 or informationto be transmitted from the UE 20, and the memory 24, which may bereplaced with an element such as a buffer (not shown), may store theprocessed information for a predetermined time.

The configurations of the transmit point apparatus and the UE asdescribed above may be implemented such that the above-describedembodiments can be independently applied or two or more thereof can besimultaneously applied, and description of redundant parts is omittedfor clarity.

Description of the transmit point apparatus 10 in FIG. 24 may be equallyapplied to a relay as a downlink transmitter or an uplink receiver, anddescription of the UE 20 may be equally applied to a relay as a downlinkreceiver or an uplink transmitter.

The embodiments of the present invention may be implemented throughvarious means, for example, hardware, firmware, software, or acombination thereof.

When implemented as hardware, a method according to embodiments of thepresent invention may be embodied as one or more application specificintegrated circuits (ASICs), one or more digital signal processors(DSPs), one or more digital signal processing devices (DSPDs), one ormore programmable logic devices (PLDs), one or more field programmablegate arrays (FPGAs), a processor, a controller, a microcontroller, amicroprocessor, etc.

When implemented as firmware or software, a method according toembodiments of the present invention may be embodied as a module, aprocedure, or a function that performs the functions or operationsdescribed above. Software code may be stored in a memory unit andexecuted by a processor. The memory unit is located at the interior orexterior of the processor and may transmit and receive data to and fromthe processor via various known means.

Preferred embodiments of the present invention have been described indetail above to allow those skilled in the art to implement and practicethe present invention. Although the preferred embodiments of the presentinvention have been described above, those skilled in the art willappreciate that various modifications and variations can be made in thepresent invention without departing from the spirit or scope of theinvention. For example, those skilled in the art may use a combinationof elements set forth in the above-described embodiments. Thus, thepresent invention is not intended to be limited to the embodimentsdescribed herein, but is intended to accord with the widest scopecorresponding to the principles and novel features disclosed herein.

The present invention may be carried out in other specific ways thanthose set forth herein without departing from the spirit and essentialcharacteristics of the present invention. Therefore, the aboveembodiments should be construed in all aspects as illustrative and notrestrictive. The scope of the invention should be determined by theappended claims and their legal equivalents, and all changes comingwithin the meaning and equivalency range of the appended claims areintended to be embraced therein. The present invention is not intendedto be limited to the embodiments described herein, but is intended toaccord with the widest scope consistent with the principles and novelfeatures disclosed herein. In addition, claims that are not explicitlycited in each other in the appended claims may be presented incombination as an embodiment of the present invention or included as anew claim by subsequent amendment after the application is filed.

INDUSTRIAL APPLICABILITY

The embodiments of the present invention can be applied to variousmobile communication systems.

What is claimed is:
 1. A method for a user equipment (UE) in a wirelesscommunication system, the method comprising: transmitting, by the UE, aPhysical sidelink control channel (PSCCH); and transmitting, by the UE,a Physical sidelink shared channel (PSSCH) related to the PSCCH, whereina sequence for the PSSCH is based on a value related to a Cyclicredundancy check (CRC).
 2. The method of claim 1, wherein the sequenceis a reference signal sequence for the PSSCH.
 3. The method of claim 1,wherein the sequence is a scrambling sequence for the PSSCH.
 4. Themethod of claim 1, wherein the CRC is a CRC on the PSCCH.
 5. The methodof claim 1, wherein the UE is capable of communicating with at least oneof another UE, a UE related to an autonomous driving vehicle, a basestation (BS) or a network.
 6. A user equipment (UE) in a wirelesscommunication system, the UE comprising: at least one processor; and atleast one computer memory operably connectable to the at least oneprocessor and storing instructions that, when executed, cause the atleast one processor to perform operations comprising: transmitting, bythe UE, a Physical sidelink control channel (PSCCH); and transmitting,by the UE, a Physical sidelink shared channel (PSSCH) related to thePSCCH, wherein a sequence for the PSSCH is based on a value related to aCyclic redundancy check (CRC).
 7. The UE of claim 6, wherein thesequence is a reference signal sequence for the PSSCH.
 8. The UE ofclaim 6, wherein the sequence is a scrambling sequence for the PSSCH. 9.A processor for transmitting a Physical Sidelink Shared Channel (PSSCH)in a wireless communication system, wherein the processor is configuredto perform operations for a user equipment (UE), wherein the operationsinclude: transmitting, by the UE, a Physical sidelink control channel(PSCCH); and transmitting, by the UE, the PSSCH related to the PSCCH,and wherein a sequence for the PSSCH is based on a value related to aCyclic redundancy check (CRC).
 10. The processor of claim 9, wherein thesequence is a reference signal sequence for the PSSCH.
 11. The processorof claim 9, wherein the sequence is a scrambling sequence for the PSSCH.12. A non-transitory computer-readable storage medium storing at leastone computer program including instructions which, when executed by atleast one processor, cause the at least one processor to performoperations for a user equipment (UE), wherein the operations include:transmitting, by the UE, a Physical sidelink control channel (PSCCH);and transmitting, by the UE, a Physical sidelink shared channel (PSSCH)related to the PSCCH, and wherein a sequence for the PSSCH is based on avalue related to a Cyclic redundancy check (CRC).
 13. The non-transitorycomputer-readable storage medium of claim 12, wherein the sequence is areference signal sequence for the PSSCH.
 14. The non-transitorycomputer-readable storage medium of claim 12, wherein the sequence is ascrambling sequence for the PSSCH.